Metal oxide oil slurries

ABSTRACT

A highly stable metal oxide oil slurry useful in reducing slag, facilitating removal of deposits from boiler tubes, and reducing corrosion on the heating surfaces of boilers has been developed. Such a slurry consists essentially of about 50% by weight magnesium oxide or the entity of magnesium oxide and alumina oxide, together with an oil-soluble emulsifier such as alkanolamide and preferably ethanolamide, or an alkanol with a carbon chain greater than a C3 alcohol, an oil-soluble dispersant such as a C12-C22 entity selected from an unsaturated or saturated fatty acid; e.g., oleic acid. Also, as a constituent is an anionic surfactant such as magnesium lauryl sulfate in an oil base such as No. 2 fuel oil. The alkanolamide is fashioned from heating alkanolamines and fatty acids either in a 1:1 ratio or 2:1 ratio. The reactant amino alcohol is in the range C10-C24. The alcohol itself is greater than C3 and up to C16, with a preferred range C12-C16.

This is a continuation-in-part application of pending Ser. No. 101,938 filed Dec. 10, 1979, now abandoned.

This invention is a highly stable metal oxide oil slurry useful in reducing slag, facilitating removal of deposits from boiler tubes, and reducing corrosion on the heating surfaces of boilers. Such a slurry consists essentially of about 50% by weight magnesium oxide or the entity of magnesium oxide and alumina oxide, together with an oil-soluble emulsifier such as an alkanolamide or an alkanol with a carbon chain greater than a C₃ alcohol, an oil-soluble dispersant such as a C₁₂ -C₂₂ entity selected from an unsaturated or saturated fatty acid such as oleic acid. Also, as a necessary constituent is an anionic surfactant such as magnesium lauryl sulfate in an oil base such as No. 2 fuel oil. The alkanolamide is fashioned from heating alkanolamines and fatty acids either in a 1:1 ratio or 2:1 ratio. The reactant amino alcohol is in the range C₁₀ -C₂₄. The alcohol itself is greater than C₃ and up to C₁₆, with a preferred range C₁₂ -C₁₆. The acid which is reacted to produce the alkanolamide is selected from a C₁₂ -C₂₂ entity such as oleic acid, etc. The alcohol defined as greater than C₃ and which reacts with the amine to produce the alcohol amine may be greater than C₃ and up to C₁₆ and it is noted that the optimum detergent range is C₁₂ -C₁₆.

Specialty oil slurries have been successfully developed for the application of reducing slagging, facilitating removal of slag and deposit from the fireside of the boiler tubes and reducing corrosion on the heating surfaces of the boilers. A generalized recipe of a typical composition is set out below.

    ______________________________________                                                        Narrow       Broad                                              ______________________________________                                         Metal oxide      50% by wt.     45-55%                                         Alkanolamide; e.g.,                                                            ethanolamide     1% by wt.      1-3%                                           Oleic acid       4% by wt.      2-6%                                           Oil insoluble thickening                                                       and stabilizing agents                                                         (anionic surfactants);                                                         e.g., salts of alkyl                                                           sulfate, magnesium lauryl                                                      sulfate          2% by wt.      1-3%                                           No. 2 fuel oil   43% by wt.     Balance                                        ______________________________________                                    

A preferred oil is heavy aromatic naphtha.

Also, a recipe of more particular components is set out below:

    ______________________________________                                         45-55%      by weight of magnesium oxide or the                                            entity of magnesium oxide and alumina                                          oxide                                                              1-3%        by weight of alkanolamide                                          2-6%        by weight of oleic acid                                            1-3%        by weight of magnesium lauryl sulfate                              Balance hydrocarbon oil                                                        ______________________________________                                    

INDIVIDUAL COMPONENTS

The emulsifier and wetting agent are preferably non-ionic surfactants; for example, alkanolamides or alcohols of chain links greater than C₃. The oil-soluble dispersant and stabilizer are preferably unsaturated and saturated fatty acids of chain link C₁₂ -C₂₂ ; for example, oleic acid. The oil-insoluble thickening and stabilizing agents are anionic surfactants preferably salts of alkyl sulfates and alkyl aryl sulfonates; for example, magnesium lauryl sulfate.

TEMPERATURE AND TIME

The slurry is stable at ambient temperature and at 135° F. for an extended period of time (greater than three months). It is believed that the slurry as formed is stabilized through the formation and interaction of hydrophilic cores with lypophilic tails of the micelles. For example, a stable slurry was obtained by mixing 1 part alkanolamide with 4 parts oleic acid, 43 parts No. 2 fuel oil, 45.45 parts magnesium oxide, 4.55 parts alumina trihydrate, and 2 parts magnesium lauryl sulfate. The slurries are sterically stabilized by this new technique involving the formation of micelles and micelle-like network structures. A uniqueness was found in its good stability at moderate temperatures as shown above and also a smoother manufacturing process and good pourability.

THE EMULSIFIERS AND METAL OXIDES

With reference to the emulsifiers, a preferred alkanolamide is Witcamide 5138 (Witco Chemical Company). In the area of the metal oxide a preferred embodiment of alumina trihydrate is Alcoa C-330.

While it is noted that the particle size of the MgO material is predominantly in the 4-6 micron range, processing this material according to steps disclosed later in this specification produces a material having a particle size in the less than 2 micron size range.

It is to be noted that the above-described magnesium oxide slurry is only a preferred embodiment of this invention and other magnesium oxides containing from 20-70% and preferably 30-60% by weight magnesium oxide-hydroxide can be employed. The particle size distribution of the magnesium hydroxide slurry which is employed in the instant invention can range from 50 down to less than 2 microns. Preferably, the material should be a particle size in the range of about 30-2 microns. The magnesium hydroxide slurry thus described is further processed into the unique material of this invention.

THE HYDROCARBON OIL

The hydrocarbon oil utilized in this invention and which permits utilization of the parameter heavy oil and high aromatic oil is justified by reference to the ASTM detailed requirements for fuel oil. It is noted that in the gradation which appears in Perry's Chemical Engineers Handbook, 5th edition, 1973, page 9-9 (reproduced below) No. 5 and 6 are heavy oils so that the terms "high" and "heavy" have definite meaning in the oil industry.

                                      TABLE 1                                      __________________________________________________________________________     A.S.T.M. Detailed Requirements for Fuel Oils*                                                                    Carbon   Distillation                                                     Water                                                                               residue  Temperature,                                           Flash                                                                               Pour and  on 10%   °F. (°C.)             Fuel               point,                                                                              point                                                                               sediment,                                                                           bottoms,                                                                            Ash,                                                                               10%                                                                               90%                              oil  Description and                                                                              °F. (°C.)                                                             °F (°C.)                                                              vol. %                                                                              %    Wt. %                                                                              Point                                                                             Point                            grade                                                                               requirements for use                                                                         Min. Max. Max. Max. Max.                                                                               Max.                                                                              Min.                                                                              Max.                          __________________________________________________________________________     No. 1                                                                               A distillate oil intended                                                                    100 or                                                                               0   Trace                                                                               0.15 --  420                                                                               -- 550                                for vaporizing pot-type                                                                      legal                   (215) (288)                              burners and other burners                                                                    (38)                                                             requiring this grade of fuel                                              No. 2                                                                               A distillate oil for general-                                                                100 or                                                                               20  0.10 0.35 --  -- 540                                                                               640                                purpose domestic heating                                                                     legal                                                                               (-7)                  (282)                                                                             (338)                              for use in burners not                                                                       (38)                                                             requiring No. 1 fuel oil                                                  No. 4                                                                               Preheating not usually re-                                                                   130 or                                                                              20   0.50 --   0.10                                                                               -- -- --                                 quired for handling or                                                                       legal                                                                               (-7)                                                        burning       (55)                                                        No. 5                                                                               Preheating may be required                                                                   130 or                                                                              --   1.00 --   0.10                                                                               -- -- --                            (light)                                                                             depending on climate and                                                                     legal                                                            equipment     (55)                                                        No. 5                                                                               Preheating may be required                                                                   130 or                                                                              --   1.00 --   0.10                                                                               -- -- --                            (heavy)                                                                             for burning and, in cold                                                                     legal                                                            climates, may be required                                                                    (55)                                                             for handling                                                              No. 6                                                                               Preheating required for                                                                      150  --   2.0  --   --  -- -- --                                 burning and handling                                                      __________________________________________________________________________      *A.S.T.M. Burner Fuel Specification D 396 [from Perry's Chemical Engineer      Handbook, 5th ed., 1973, page 99]-                                       

EXAMPLE 1

A number of exemplary recipies were made up embodying this example:

    ______________________________________                                         (A)    No. 2 fuel oil       45.8   wt. %                                              Magnesium oxide                                                                (Martin Marietta                                                               Grade 469)           50.0   wt. %                                              NINOL 201* (ethanolamide                                                       oleic acid)          2.2    wt. %                                              Magnesium lauryl sulfate                                                                            2.0    wt. %                                       (B)    NINOL 201* (ethanolamide                                                       oleic acid)          2.2    wt. %                                              Oleic acid           4.5    wt. %                                              Hydrocarbon oil      41.8   wt. %                                              Magnesium oxide                                                                (Martin Marietta                                                               Grade 469)           45.45  wt %                                               Al.sub.2 O.sub.3.3H.sub.2 O                                                                         4.55   wt %                                               Diethanolamine lauryl                                                          sulfate (Stepanol DEA)                                                                              1.5    wt %                                        ______________________________________                                          *NINOL (Stepan Chemical Company, Northfield, Illinois).                        Witcamide 5138 (Witco Chemical Company, New York, New York), may be            substituted for the NINOL compounds above.                               

EXAMPLE 2

Standard Procedure of Making Slurries

    ______________________________________                                         Typical Composition Percent                                                            All                                                                             siumne-Mag-                                                                         ##STR1##                                                                                     ##STR2##                                           ______________________________________                                         Alkanolamide                                                                              1.80  2.00          1.80                                            Oleic acid                                                                                6.00  5.50          4.50                                            Oil (Exxon)                                                                              39.70  40.30         41.30                                           MgO       50.00  45.45         33.33                                           Al.sub.2 O.sub.3.3H.sub.2 O                                                              --     4.55          16.67                                           Diethanolamine                                                                 lauryl sulfate                                                                            2.50  2.20          2.40                                            ______________________________________                                    

PROCEDURE:

Mix emulsifier and dispersant with oil until homogeniety is achieved, usually 10 minutes.

Charge MgO and Al₂ O₃.3H₂ O to the mixture and mix for one-half hour.

Charge thickener and continue mixing for 15 minutes.

Store the slurry in a closed container.

COMBINATION OF EMULSIFIER WITH OLEIC ACID

Mix 2% emulsifier, 43% oil, with 5% oleic acid.

Charge MgO until viscosity reaches ˜8,000 cps.

Observe stability at room temperature and at 135° F.

THICKENER

Mix 1 to 4% thickener to either single or dual surfactants-slurry.

Record the viscosity increases.

Observed stability at room temperature and at 135° F.

EXAMPLE 3a

    ______________________________________                                         Lauric acid amide   2.00                                                       Oleic acid          6.00                                                       Oil (Exxon), high aromatic                                                                         40.50                                                      MgO                 45.45                                                      Al.sub.2 O.sub.3.3H.sub.2 O                                                                        4.55                                                       Diethanolamine lauryl                                                          sulfate             1.50                                                       ______________________________________                                    

EXAMPLE 3b

    ______________________________________                                         High Alumina                                                                   ______________________________________                                         Coconut oil amide 1.80                                                         Ammonium Alkyl                                                                 sulfate           1.50                                                         Alumina trihydrate                                                             (Alcoa, C-330)    16.67                                                        Oleic acid        5.50                                                         MgO               33.33                                                        Heavy naphtha oil 41.20                                                        ______________________________________                                    

EXAMPLE 4

    ______________________________________                                         Stearic acid alkanolamide                                                                        15     g       0.5  wt. %                                    Oleic acid        165    g       5.5  wt. %                                    Oil               1260   g       42.0 wt. %                                    MgO               1365   g       45.45                                                                               wt. %                                    Al.sub.2 O.sub.3.3H.sub.2 O                                                                      135    g       4.55 wt. %                                    Magnesium alkyl sulfate                                                                          60     g       2.0  wt. %                                    ______________________________________                                     

We claim:
 1. A metal oxide slurry consisting essentially of:(a) about 50% by weight of magnesium oxide or the entity of magnesium oxide plus alumina (b) about 1% by weight of an oil-soluble emulsifier and wetting agent (c) about 4% by weight of an oil-soluble dispersant (d) about 2% by weight of an insoluble thickening agent (e) about 43% by weight, or a balance, of a hydrocarbon oil.
 2. A metal oxide oil slurry consisting essentially of:(a) about 50% by weight of magnesium oxide (b) about 1% by weight of alkanolamide (c) about 4% by weight of oleic acid (d) about 2% by weight of magnesium lauryl sulfate (e) about 43% by weight of hydrocarbon oil.
 3. A metal oxide oil slurry consisting essentially of:(a) 45-55% by weight of magnesium oxide or the entity of magnesium oxide and alumina oxide (b) 1-3% by weight of alkanolamide (c) 2-6% by weight of oleic acid (d) 1-3% by weight of magnesium lauryl sulfate (e) the balance hydrocarbon oil.
 4. The slurry according to claim 2 wherein the alkanolamide is ethanolamide.
 5. The oil slurry according to claim 3 wherein the percentile of magnesium oxide is 45% by weight and the percentile of alumina is 5% by weight.
 6. A metal oxide oil slurry consisting essentially of 1 part alkanolamide mixed with 4 parts oleic acid; 43 parts No. 2 fuel oil; 45.45 parts magnesium oxide; 4.55 parts alumina trihydrate; 2 parts maleic lauryl sulfate. 